1. Field of the Invention
The invention relates generally to photographic cameras, and more particularly to film threading and film rewind means in such cameras.
2. Description of the Prior Art
The film loading procedure for many 35 mm cameras, such as the Nikon single-lens-reflex models, e.g., the Nikon FA, is substantially the same. This procedure is typically as follows:
1. the film rewind knob is pulled up from the camera body, partially withdrawing the rewind key shaft from the film cartridge chamber;
2. the camera back is pivoted open;
3. the film cartridge is positioned in the cartridge chamber with the film leader pointing towards the take-up drum in the film take-up chamber;
4. the rewind knob is pushed down, moving the keyed end of the rewind shaft into a keyhole in one end of the film spool in the cartridge, and thereby securing the cartridge in place;
5. the film leader is pulled across the exposure frame located between the cartridge chamber and the take-up chamber, and is secured to the take-up drum; and
6. the camera back is closed.
To unload the film from the camera, after the film (except for an end portion secured to the film spool in the cartridge) has been exposed and wound onto the take-up drum, the rewind knob is rotated in the direction indicated by an arrow on the knob. Since the film spool will be similarly rotated, the film is rewound from the take-up drum into the cartridge. Then, the rewind knob is pulled up from the camera body, removing the keyed end of the rewind shaft from the keyhole in one end of the film spool, and the camera back is opened, thereby permitting the cartridge to be removed from the cartridge chamber.
Each of the steps in these procedures for film loading and film unloading, though relatively easy to follow, must be done manually and in the specified order. Thus, there are presented certain limitations or shortcomings. For example, successful film loading and unloading requires that the operator strictly adhere to the respective procedures. The omission of a step in either one of the procedures, or a deviation from the step, will result in a problem. Moreover, as with any manual procedure, a certain amount of attention and skill is required.
SUMMARY OF THE INVENTION
The invention simplifies film loading in a photographic camera of the type provided with (a) a chamber adapted to receive a film cartridge having an engageable spool about which the film is wound, (b) take-up means for advancing the film from the cartridge, (c) a rewind member movable in the chamber into engagement with the spool for securing the cartridge in place during advancement of the film from the cartridge and for rotating the spool to rewind the film into the cartridge, and (d) a camera back movable to open and close the chamber, by the improvement comprising:
means supporting the camera back for closing movement in the same direction the take-up means advances the film from the cartridge;
motion imparting means for moving the rewind member into engagement with the spool in response to closing movement of the camera back; and
threading means connected to the camera back for engaging the film to thread the film to the take-up means during closing movement of the camera back.
According to the invention, therefore, closing movement of the camera back (i) effects movement of the rewind member into engagement with the spool in the cartridge to secure the cartridge in place and (ii) causes the film leader to be threaded from the cartridge to the take-up means. Thus, except for inserting the cartridge in the chamber and closing the camera back, film loading is effected automatically, rather than manually as in the prior art procedure described above.
In a preferred embodiment of the invention, cooperating means connected to the rewind member and the camera back couple the two to move the rewind member into engagement with the spool in the cartridge in response to closing movement of the camera back, and uncouple the two to permit the rewind member to be moved out of engagement with the spool in response to opening movement of the camera back. Spring means urge the rewind member to move out of engagement with the spool. Thus, the rewind member is moved into and out of engagement with the spool (to secure and release the cartridge) in response to closing and opening movement of the camera back, respectively, thereby facilitating film unloading as well as film loading.